Ctin mRNA level. The mRNA expression level of CaM significantly increased at 1 day and 4 days after SPS but did not change in control rats, and then recovered to normal level at 7 days after SPS. In contrast, the mRNA expression level of CaMKIIa markedly decreased at 1 day and 4 days after SPS (Fig. 9A, 9B).DiscussionPTSD is a stress-related mental disorder caused by experience of a traumatic event, and presents with characteristic symptoms including re-experiencing symptoms (e.g., nightmares and flashbacks), hyperarousal symptoms (e.g., insomnia), numbing symptoms (e.g., 10457188 restricted affect and anhedonia), avoidance symptoms(e.g., avoiding trauma-related stimuli), poor concentration and difficulty explicitly recalling aspects of the traumatic event. Magnetic resonance imaging studies showed decreased volume 16574785 of the hippocampus in PTSD patients [30], suggesting a strong relationship between atrophy of the hippocampus and PTSD. Other studies from our team examined apoptosis in the hippocampus [9], amygdale [10] and cortex (unpublished data) of the single prolonged stress (SPS) rats. In this study, apoptotic cells were significantly increased in the hippocampus of the SPS rat as detected by TUNEL method. Consistent with this, apoptotic morphological changes were found in hippocampal neurons of SPS rats, including plasma membrane blebbing, cell shrinkage, chromatin condensation, and nuclear pyknosis. These observations indicate that SPS could induce neuronal apoptosis in hippocampus and that apoptosis may be one of the causes of hippocampal dysfunction. Recently, it has been reported that endoplasmic reticulum also mediates apoptosis. The efficient functioning of the endoplasmic reticulum is essential for most cellular activities and survival. Many acute and chronic neurodegenerative disorders lead to accumulation of unfolded proteins and induce the unfolded protein response (UPR) [31]. The objective of UPR is to quickly reduce the requirement for ER protein processing and to eliminate the misfolded proteins as rapidly as possible. The protein degradation mechanism includes transporting the misfolded proteins out of the ER to the cytoplasm through a translocon. When the capacity of the ER to cope is saturated, UPR induces production of molecularER- Pathway is Involved in PTSD-Induced ApoptosisFigure 9. order (��)-Imazamox RT-PCR of CaM/CaMKIIa in the hippocampus of SPS rats. Calmodulin (CaM) and CaM kinase IIa (CaMKIIa) mRNA expression (A) and results from its quantitative analysis (B). Increased CaM and decreased CaMKIIa expression levels were observed in the hippocampus of rats subjected to SPS while CaM and CaMKIIa expression levels were unchanged in control rats. *P,0.05 vs. the control group, #P,0.05 vs. the SPS 1 day group, ^P,0.05 vs. the SPS 4 days group. doi:10.1371/journal.pone.0069340.gchaperones (GRP78) and other components, and these proteins are required for the removal of the polypeptides that fail to fold properly [19], [32]. The overall result is improvement of folding and processing efficiency, and Title Loaded From File reduction in the flow of proteins into the ER compartment. If the adaptive capacity of the UPR to handle the problem is exceeded, the UPR response includes the induction of pro-apoptotic events including the up-regulation of a number of cell death genes including caspase-12 and their eventual activation. The three primary mammalian UPR ERtransmembrane proteins that control transcription, translation, and apoptosis are PERK, IRE1a, and ATF6. All three.Ctin mRNA level. The mRNA expression level of CaM significantly increased at 1 day and 4 days after SPS but did not change in control rats, and then recovered to normal level at 7 days after SPS. In contrast, the mRNA expression level of CaMKIIa markedly decreased at 1 day and 4 days after SPS (Fig. 9A, 9B).DiscussionPTSD is a stress-related mental disorder caused by experience of a traumatic event, and presents with characteristic symptoms including re-experiencing symptoms (e.g., nightmares and flashbacks), hyperarousal symptoms (e.g., insomnia), numbing symptoms (e.g., 10457188 restricted affect and anhedonia), avoidance symptoms(e.g., avoiding trauma-related stimuli), poor concentration and difficulty explicitly recalling aspects of the traumatic event. Magnetic resonance imaging studies showed decreased volume 16574785 of the hippocampus in PTSD patients [30], suggesting a strong relationship between atrophy of the hippocampus and PTSD. Other studies from our team examined apoptosis in the hippocampus [9], amygdale [10] and cortex (unpublished data) of the single prolonged stress (SPS) rats. In this study, apoptotic cells were significantly increased in the hippocampus of the SPS rat as detected by TUNEL method. Consistent with this, apoptotic morphological changes were found in hippocampal neurons of SPS rats, including plasma membrane blebbing, cell shrinkage, chromatin condensation, and nuclear pyknosis. These observations indicate that SPS could induce neuronal apoptosis in hippocampus and that apoptosis may be one of the causes of hippocampal dysfunction. Recently, it has been reported that endoplasmic reticulum also mediates apoptosis. The efficient functioning of the endoplasmic reticulum is essential for most cellular activities and survival. Many acute and chronic neurodegenerative disorders lead to accumulation of unfolded proteins and induce the unfolded protein response (UPR) [31]. The objective of UPR is to quickly reduce the requirement for ER protein processing and to eliminate the misfolded proteins as rapidly as possible. The protein degradation mechanism includes transporting the misfolded proteins out of the ER to the cytoplasm through a translocon. When the capacity of the ER to cope is saturated, UPR induces production of molecularER- Pathway is Involved in PTSD-Induced ApoptosisFigure 9. RT-PCR of CaM/CaMKIIa in the hippocampus of SPS rats. Calmodulin (CaM) and CaM kinase IIa (CaMKIIa) mRNA expression (A) and results from its quantitative analysis (B). Increased CaM and decreased CaMKIIa expression levels were observed in the hippocampus of rats subjected to SPS while CaM and CaMKIIa expression levels were unchanged in control rats. *P,0.05 vs. the control group, #P,0.05 vs. the SPS 1 day group, ^P,0.05 vs. the SPS 4 days group. doi:10.1371/journal.pone.0069340.gchaperones (GRP78) and other components, and these proteins are required for the removal of the polypeptides that fail to fold properly [19], [32]. The overall result is improvement of folding and processing efficiency, and reduction in the flow of proteins into the ER compartment. If the adaptive capacity of the UPR to handle the problem is exceeded, the UPR response includes the induction of pro-apoptotic events including the up-regulation of a number of cell death genes including caspase-12 and their eventual activation. The three primary mammalian UPR ERtransmembrane proteins that control transcription, translation, and apoptosis are PERK, IRE1a, and ATF6. All three.
